Mechanical strength - Page 6

Bloomberg posted an interesting article on Applied Graphene Materials, the graphene maker that was established in 2010 as a spin-off from Durham University to develop a new CVD-based graphene synthesis method and produce graphene materials. The company's CEO, Jon MabbitT, details some interesting new applications they are trying to develop.

AGM is currently targeting two types of applications. First up are early-adopters, such as Formula 1 teams. But AGM is also looking to enter into long-term products - mainly in the aerospace industry. Graphene can enable stronger and lighter materials, suitable for aircraft. AGM is also working with Dyson (vacuum cleaner developer), Procter & Gamble, lubricants makers and wind-turbine developers. Finally, they are developing an impermeable rustproof coatings for ships.

Researchers from Penn State University developed a new ultra-thin and super strong material that is made from the same hexagonal rings of bonded carbon atoms that make up diamonds. The so called diamond nanothreads may prove to be the strongest man-made material ever developed.

The new material was produced using a pressure device to compress an especially large 6 mm wide pool of benzene (a carbon and hydrogen molecule). The benzene molecules broke under the pressure, and when the pressure was released, they formed the diamond configuration of the nanothreads.

Researchers from Korea's Hanyang University developed new hybrid graphene-CNT fiber that is at least 12 times stronger compared to a general Kevlar fibers used in current bulletproof jackets. The new fiber is also more flexible.

To produce the new fibers, the researchers started out by dispersing graphene in water, which were then dispersed in a polymer solution using wet spinning to obtain a fiber form. The polymer was later removed, which created pure graphene fibers, which were later mixed with carbon-nanotubes fibers.

Researchers from Boston University discovered that making patterned cuts in graphene can enable it to become stretchable - to more than 160% of their original size (regular graphene will be torn after stretched by 30%). This research uses an approach that is similar to the Japanese paper-cutting technique kirigami. The researchers say that it such stretchable graphene can be used to fabricate flexible sensors or foldable TV screens.

The researchers have used computer simulations, and have not performed real experiments yet. Those patterned sheets look like intricate snowflakes or flowers. The best pattern, they discovered, was numerous overlapping rectangles.

One of the projects that was selected for the 2nd-stage of the EU's Graphene Flagship initiative is called iGCAuto, led by the University of Sunderland. This project partners will try and see how graphene and graphene-composite materials an be used in the automotive industry.

The focus of the project will be to find new materials that can make vehicles lighter and safer. The partners include Fiat, the Fraunhofer ICT, Interquimica, Nanesa and Delta-Tech. The partners will investigate different nanocomposites with different polymer matrices.

Researchers from Penn State University and Japan's Shinshu University developed a simple and scalable process to make strong, stretchable graphene oxide fibers. Those fibers can easily be scrolled into yarns that have strengths approaching that of Kevlar.

The new GO fiber is the strongest carbon fiber ever. The researchers believe that pockets of air inside the fiber keep it from being brittle. But those fibers can also be altered to make other useful materials. For example, removing the oxygen results in a fiber with high electrical conductivity, while adding silver nanorods increases the conductivity (to the same level as copper, while being much lighter than copper).

Last month we reported that researchers from Beijing are developing graphene-enhanced titanium alloys that may be useful as a new material for aircraft. Today we learn that the Chinese are not alone in their graphene efforts for the aerospace industry.

So first up with a new research by the University of Manchester, that developed new carbon fibers using a composite material made from two layers of polymer with a graphene sheet placed between them. Using Raman Spectroscopy, the researchers measured these fibers and found them to be very strong, even when stretched. The researchers say that these can be used to make structural, lightweight components for fuel efficient cars and aircraft.

Haydale published a research showing that its functionalised graphene nanoplatelets (GNPs) significantly improve the nanoreinforcement of resin. This research was conducted conducted by the Material Science Department at AeroSpace Corporation.

According to the report, graphene can significantly strengthen toughened epoxy composites. The reported increases are >2x in tensile strength and modulus of an epoxy composite using a number of Haydale's HDPlas O2-functionalised GNP. The addition of increasing amounts of GNP resulted in strength increases of over 125% and toughness improvements of 100% over that of similarly cured, unreinforced material.

Researchers from the Beijing Institute of Aeronautical Materials developed a new material that combines graphene and aluminum alloy. The institute aims to use this strong material to enhance titanium alloys - and produce new materials for aircrafts.

This material has a yield strength of 58% and a tensile strength of 25% - which are excellent properties for making high-end alloys.

Researchers from Rice University and Georgia Tech measured the fracture toughness of imperfect graphene for the first time and found it to be somewhat brittle. It turns out that graphene is really only as strong as its weakest link, and this can make a defected graphene substantially less strong than a perfect graphene.

According to the researchers, graphene follows the century-old Griffith theory that quantifies the useful strength of brittle materials. Imperfections in graphene drastically lessen its strength (which has an upper limit of about 100 gigapascals for a perfect graphene).